Tens of thousands of supporters of presidential hopeful Ahmed Shafiq gathered in Nasr City on Saturday, one day before the election results are expected to be announced, chanting against the Muslim Brotherhood's candidate, Mohamed Mursi, Shafiq's runoff rival, Ahram Online reported.
Protesters, holding aloft banners branded with Shafiq's image, chanted "Down with the rule of the Supreme Guide" and "No to Brotherhood, no to Salafists; they market in the name of religion."
The demonstration blocked Nasr Street, leading to considerable traffic congestion in surrounding areas.
Earlier on Saturday, Egypt's Presidential Electoral Commission announced that presidential election results will be announced on Sunday at 3pm (1pm GMT).